The present invention generally relates to material handling apparatus and, in a preferred embodiment thereof, more particularly relates to excavating apparatus, representatively a tracked excavator, having operatively attached to the stick portion of its boom a specially designed combination bucket and breaker structure which uniquely permits the excavator operator to selectively carry out either digging or refusal material breaking tasks without having to change out equipment on the stick.
Large scale earth excavation operations are typically performed using a powered excavating apparatus, such as a tracked excavator, having an articulated, hydraulically pivotable boom structure with an elongated, pivotal outer end portion commonly referred to as a xe2x80x9cstickxe2x80x9d. Secured to the outer end of the stick is an excavating bucket which is hydraulically pivotable relative to the stick between xe2x80x9cclosedxe2x80x9d and xe2x80x9copenxe2x80x9d positions. By pivotally manipulating the stick, with the bucket swung to a selected operating position, the excavator operator uses the bucket to forcibly dig into the ground, scoop up a quantity of dirt, and move the scooped up dirt quantity to another location, such as into the bed of an appropriately positioned dump truck.
A common occurrence during this conventional digging operation is that the bucket strikes refusal material (in excavation parlance, a material which xe2x80x9crefusesxe2x80x9d to be dug up) such as rock which simply cannot be broken and scooped up by the bucket when this occurs it is typical practice to stop the digging operation, remove the bucket from the stick, and install a hydraulically operated xe2x80x9cbreakerxe2x80x9d on the outer end of the stick in place of the removed bucket. The breaker has, on its outer end, an oscillating tool portion which rapidly hammers the refusal material in a manner breaking it up into portions which can be subsequently dug up. After the breaker has been utilized to break up the refusal material, the operator removes the breaker from the stick, replaces the breaker with the previously removed bucket, and resumes the digging operation with the bucket.
While this procedure is easy to describe, it is a difficult, laborious and time consuming task for the operator to actually carry out due to the great size and weight of both the bucket and breaker which must be attached to and then removed from the breaker, and the necessity for the operator to climb into and out of the high cab area of the excavator (often in inclement weather) to effect each bucket and breaker changeout on the stick. This sequence of bucket/breaker/bucket changeout, of course, must be laboriously repeated each time a significant refusal area is encountered in the overall digging process.
A previously utilized alternative to this single excavator sequence, is to simply provide two excavators for each digging projectxe2x80x94one excavator having a bucket attached to its boom stick, and the second excavator having a breaker attached to its boom stick. When the bucket-equipped excavator encounters refusal material during the digging process, it is simply moved away from the digging site, and the operator climbs down from the bucket-equipped excavator, walks over to and climbs up into the breaker-equipped excavator, drives the breaker-equipped excavator to the digging site, and breaks up the encountered refusal material. Reversing the process, the operator then switches to the bucket-equipped excavator and resumes the digging process to scoop up the now broken-up refusal material.
While this digging/breaking technique is easier on the operator, it is necessary to dedicate two large and costly excavators to a given digging task, thereby substantially increases the total cost of a given excavation task. A modification of this technique is to use two operatorsxe2x80x94one to operate the bucket-equipped excavator, and one to operate the breaker-equipped excavator. This, of course, undesirably increases both the manpower and equipment cost for a given excavation project.
As can be readily appreciated from the foregoing, a need exists for an improved technique for carrying out the requisite digging and refusal material breaking portions of an overall excavation operation in a manner eliminating or at least substantially eliminating the above-mentioned problems, limitations and disadvantages commonly associated with conventional digging and breaking operations. It is to this need that the present invention is directed.
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, an excavating machine, representatively a tracked excavator, is provided with a specially designed pivotable boom stick assembly that includes a boom stick having first and second excavating tools secured thereto for movement relative to the boom stick. Illustratively, the first excavating tool is an excavating bucket secured to the boom stick for pivotal movement relative thereto between a first position and a second position, and the second tool is a breaker secured to the boom stick for pivotal movement relative thereto between a stowed position and an operative position.
Hydraulically operable drive apparatus is interconnected between the boom stick and the bucket and breaker and is useable to pivotally move the bucket between its first and second positions, and to pivotally move the breaker between its stowed and operative positions. Representatively, the drive apparatus includes a plurality of hydraulic cylinder assemblies operatively interconnected between the boom stick and the bucket and breaker.
The bucket, when the breaker is in its stowed position, is movable by the drive apparatus to the second bucket position and is useable in conjunction with the boom stick, and independently of the breaker, to perform a digging operation. The breaker, when the bucket is in its first position, is movable by the drive apparatus to the breaker""s operative position and is useable in conjunction with the boom stick, and independently of the bucket, to perform a breaking operation. Accordingly, the excavating machine may be advantageously utilized to perform both digging and breaking operations without equipment changeout on the boom stick.
In an illustrated preferred embodiment thereof, the excavating machine is also provided with control circuitry coupled to the drive apparatus and useable to operate it. Representatively, the control circuitry includes a hydraulic flow circuit in which the drive apparatus is interposed; a flow controller operative to selectively reverse the direction of hydraulic fluid flow through a portion of the hydraulic flow circuit; diverting valve apparatus interconnected in the hydraulic flow circuit and operable to selectively route hydraulic fluid through the hydraulic flow circuit to (1) a first portion of the drive apparatus associated with the bucket, or (2) a second portion of the drive apparatus associated with the breaker; and a switch structure useable to selectively operate the diverting valve apparatus.